I recently replaced cables on my W51 (not WT51). The lower lifting cable was 3/16" diameter and 37'-6" long. The upper section cable was also 3/16" diameter and 19'-5.5" long. The tower is mid-1960's
Allen, Over the past year I have had much discussion with some structural engineers that I work with about this very subject - at least as it pertains to a couple of self supporting tower installatio
In response to the thread about crank-up tower failures I put some selected output views from a finite element stress analysis of my LM-470 loaded to theoretical yield failure at: http://www.flukey.c
The drag coefficient may be 1/2, but when multiplied by 400% more face area is the drag not 2x? KM5VI And I'm not sure that specifying "round members" is valid. Members in the 1-4" range at 70mi/hr
Just a thought... Could the corrosion on the surface of the steel radial wires be presenting a high RF impedance (relative to the ground rod path) when dry due to RF skin effect? Perhaps either the m
I would forget the 1/2 wave vertical dipole unless you are near saltwater. I would go with a transmit 1/4 wave vertical with the best radial field I could muster if you are QRO and try to put up some
Between the two tests you suggest, my vote would go for the later RF test. I would not assume that a DC test measurement necessarily correlates to what's occurring at HF when diagnosing a problem. Go
NEC models I ran a few years back predicted wave angle elevation patterns at varying installation heights similar to (most) any horizontal beam antenna. KM5VI Has anyone modeled hexagonal beams with
My experience with Gap is that they generally offer the potential for the lower wave angle of a vertical design but really have no gain unless you are over very conductive ground (like saltwater cond
Try Superior Bolt & Nut at 602-841-8100, 4202 E Elwood, Suite 16, Phoenix, AZ, 85040. They stock just about anything one would need in concrete anchor bolts and they are very knowledgeable. I believe
I recommend a 4-section, 36' TV-type push-up pole extended to a height of about 32 feet. Radio Shack used to sell these for about $80. I have used one for more than a decade of field operations with
Correction... >>this greatly reduces the moment loading on the anchors which increases pull-put strength and minimizes tensile bending (not shear) stress in the metal. -MF I recommend a 4-section, 36
David, First off, thanks for providing all of the great information resources over the years. Since I don't see any reply to your question yet, I'll share what I know in hopes that it may provide you
Hi Grant, Thanks for sharing. My understanding is that shear stress is not dependent on slippage since it is acting perpendicular to axial tension/compression which results from bending, so I agree w
Do you need mention but are you looking for variable or fixed direction gain? Also is wave angle important - if so what angle? Matt KM5VI Hello folks, I'd like to hear your opinions about this topic.
Here are some ideas... I once modeled and then built a fixed bi-direction vertical vee long wave antenna. The concept works on the same principle as a half-rhombic but erected vertically instead of h
Snug tight is a standard term commonly used in the design of bolted connections that are not slip-critical. Slip-critical connections rely on the friction created by the clamping action of the thread
Very well put Mickey and I agree with your 90% comment as well. Page 51 of the Research Council on Structural Connections (RCSC) Specification for Structural Joints Using High-Strength Bolts gives us
Oops - I have used the wrong term - not a spud wrench. I used a hammer wrench (aka slugging wrench or striking wrench) for the nuts on ASTM F1554 concrete anchor bolts. For A325 3/4" diameter shear b
Good point! I have both US and Tri-Ex towers - older models. The shop drawings for both of my tri-ex towers spec A307 as you say but with a bucket of A325's "use 'em if you got 'em"... which should b